Dual speed lifter for material handling machines



June 1, 1965 c. E. KILLEBREW DUAL SPEED LIFTER FOR MATERIAL HANDLING MACHINES 2 Sheets-Sheet 1 Filed Dec. 18. 1961 INVENTOR CLARENCE E. KILLEBREW ATTORNEY June 1, 1965 c. E. KILLEBREW DUAL SPEED LIFTER FOR MATERIAL HANDLING MACHINES 2 Sheets-Sheet 2 Filed Dec. 18, 1961 INVENTOR CLARENCE E. KILLEBREW ATTORNEY ing the cost of performing work with such machine.

United States Patent 3,ll8ti,3tl9 DUAL SPEED LIFTER FOR MATERIAL HANDLING MACHINES Clarence E. Kiliehrew, Coloma, Mich assignor to Clark Equipment Company, a corporation of Michigan Filed Dec. 18, 196i, Ser. No. 160,129 Claims. (Cl. 91-412) This invention relates to tractor shovels, tractor loaders and other material handling machines having an outwardly projecting boom arm or arms on which a material engaging device is carried.

It is well-known to accomplish the excavating of earth, the loading of bulk materials, and the handling of other materials by means of tractor vehicles which include a material handling bucket or other material engaging deviceas a portion of the vehicle. Commonly such a bucket or other material engaging device is mounted at the front of the vehicle on boom arms which provide for the raising and lowering of the bucket or other device between a digging or loading position and a dumping or discharge position. Some of such vehicles are adapted to excavate dirt, sand, rocks and the like below ground level and then raise the material and dump it into a truck, hopper or other receptacle, while such excavating machines can also be used merely as loaders if desired for picking up bulk materials such as crushed stone, coal, grain, fertilizer and the like, at or near ground level and loading it into a truck, hopper or other receptacle. Some such machines are less powerful and are adapted for use only as loaders and not as excavators, while still other machines are equipped with a fork device or other load engaging means instead of a bucket.

In the machines mentioned which are adapted for use as excavators, it is important that the mechanism carrying and controlling the bucket be arranged to tilt the bucket back at ground level in order to provide a break-out or pry-out action. Such an action is important in order to obtain a full bucket-load of many kinds of hard-to-excavate materials, and various arrangements have been proposed heretofore to achieve such breakout action. One of the objects of the present invention is to provide an improved construction for increasing or augmenting the break-out action of a tractor shovel.

When a vehicle of the type previously mentioned is adapted for use merely as a loader, that is, for the picking up of bulk or other materials at ground level and raising them to a higher level for dumping or dischargingusually after transporting the material between the pickup point and a discharge location-another problem is presented with conventional loader vehicles. When the boom arms of such machines are raised sufiiciently high, it is a characteristic of many such loader vehicles that the moment arm through which the actuators for the boom arms operate becomes so small that the machine is unable to raise to full height the maximum load which it can pickup at ground level, or else the raising speed is reduced significantly when a large load is being raised to the maximum height. It will be appreciated that the inability of such a machine to raise'maximum 'loads to maximum height is a serious deficiency, while even the inability to raise such loads to the maximum height quickly is undesirable because it increases the time required for performing a specific operation thereby cutting down the amount of work which the machine can perform in a certain time and consequently increas- It is a further object of the present invention to provide a structure which eliminates the mentioned disadvantages of some loader machines.

It is a still further object of this invention to carry 3,185,369 Patented June 1, I965 out either of the aforementioned objects automatically without requiring any more than the usual amount of operations on the part of the vehicle operator.

In carrying out my invention in one form I provide a tractor shovel machine having outwardly projecting boom arms which carry at the forward end thereof a bucket which is adapted for excavating. The boom arms are adapted to be raised by hydraulic actuators connected between the body of the machine and the boom arms. Each of the hydraulic actuators comprises two alongated coaxially arranged piston and cylinder devices. T he two cylinders are of different diameters and the two devices are connected together to form a composite actuator. Hydraulic connections are provided whereby the actuation of a single valve by the operator causes the larger diameter piston and cylinder device to extend first to provide a large break-out force following which the other device extends in sequence to provide for raising the boom arms after the break-out interval.

In another embodiment in a tractor loader machine the construction is similar except that the hydraulic connections are such that the smaller piston and cylinder device extends first after which the larger diameter piston and cylinder device automatically extends in sequence, the latter action providing increased raising force near the top of the travel of the boom arms.

For a clearer and more complete understanding of my invention, reference should be had to the accompanying drawing in which:

FIGURE 1 is a side elevational View of a material handling machine embodying the present invention,

FIGURE 2 is an enlarged view in section of the composite actuator utilized in one preferred form of the invention, while FIGURE 3 is an enlarged view in section. of the composite actuator utilized in another preferred form of the invention.

Referring to FIG. 1 of the drawing, the numeral 10 indicates generally a tractor vehicle embodying the present invention. The vehicle It includes a body portion 12, a pair of front drive wheels 14, only one of which is visible in the drawing, and a pair of rear drive-steer wheels 16, only one of which is visible. The vehicle is propelled by a suitable prime mover (not shown) housed within the enclosure 18, and the vehicle has an operators station at location 2! including a suitable operators steering wheel 22.

The vehicle 19 carries a bucket 24 which is shown in FIG. 1 in a ground level loading position. The bucket 24 is carried by means of a pair of main boom arms 26. Only one boom arm is visible in the drawing but it will be readily appreciated that the bucket and the arms which carry it are symmetrical about a vertical plane through the longitudinal axis of the machine. The bucket carrying mechanism also includes a pair of stabilizing or guide arms 28, one on each side of the machine below the main boom arms.

Each main boom arm is pivotally connected to the body 12 of the vehicle at location 30, while each arm 28 is pivotally connected to the body of the vehicle at 32. The bucket 2 is carried by the boom and guide arms by means of a bucket carrier 34 which is pivotally connected at 36 to the forward ends of the main boom arms and at 38 to the forward ends of the guide arms. The bucket 24 is pivotally movable about axis at) with respect to the bucket carrier :by hydraulic actuating means within carrier 34, not shown on this drawing, whereby the bucket may be pivoted rearwardly from the position shown to an upwardly disposed carrying position.

The bucket is raised and lowered by raising and lowering the main boom arms through the medium of hydraulic actuators 42. Only one of these is visible but it will be appreciated that there is preferably an actuator 42 on each side of the machine in a symmetrical arrangement. The actuator 42 is pivotally connected at location 46 to a bracket 44 which projects downwardly from the body of the vehicle. At the top the actuator 42 is pivotally connected at 48 to boom arm 26.

FIG. 2 shows the internal details of actuator 42 (indicated by the character 42a in FIG. 2) arranged to lift bucket 24 first with a large force at relatively low speed followed sequentially by a smaller force at a higher speed. The bucket 24 is shown in FIG. 1 at ground level, which ordinarily would be the loading position for loading stockpiled material or the like. It will be appreciated that the bucket 24 can be lowered below ground level when it is to be used for excavating earth. However, the actuator arrangement of FIG. 2 is useful for loading operations as well as excavating operations when the material being loaded is sufficiently packed or otherwise is of such character that it is difficult to lift the bucket through such material after the vehicle It) has been moved forwardly into the material in order to fill the bucket 24. As explained previously the bucket 24 may be pivoted counterclockwise as shown in FEG. 1 about pivot point 40 and this provides considerable breakout action. However, in some circumstances with certain materials such break-out action alone is not sufficient and in these circumstances the embodiment of the invention illustrated in FIG. 2 is very beneficial.

As shown in FIG. 2 the actuator 42:: comprises a twopart cylinder portion which is indicated generally by the numeral 50. At the left as seen in FIG. 2 the cylinder portion 50 includes a larger diameter cylinder 52, and at the right there is provided a smaller diameter cylinder 54. The two cylinder portions 52 and 54 are joined by a solid portion 56 which provides a barrier between the two cylinders and also supports the inner ends thereof to form a single unitary structure. The left end of cylinder 52 is provided with a closure member 58 while the right end of cylinder 54 is provided With a closure member 60.

A first relatively large diameter piston having a working fit inside cylinder 52 is positioned in cylinder 52 for reciprocation back and forth in this cylinder. The piston 62 is provided with packing material 64- to seal against fluid leakage past the piston. The piston 62 is mounted on and operates a piston rod 66 which extends through an opening in closure member 58; packing material 68 and a cap 70 are provided at the left to seal this end of the cylinder, while an opening 71 is provided in the wall of cylinder 52 to drain off any leakage fluid which may collect inside cylinder 52.

A smaller diameter piston 72 having packing material 74 is positioned in cylinder 54 for reciprocation therein. Piston 72 is carried by a piston rod 76 which extends through an opening in closure member 60, and packing material 78 and a cap 80 are provided to seal the outer end of cylinder 54 against dirt. A vent 82 is provided to allow the escape of any fluid which gets by piston 72.

In order to extend actuator 42a hydraulic fluid under pressure is admitted from a conduit 84 through valve 86. Conduit 84 preferably receives pressurized hydraulic fiuid from a pump operated by the engine of the vehicle in known manner, while valve 86 preferably is operated by the operator of the vehicle from his operators station thereon also in a known manner. When valve 86 is turned to the posit-ion illustrated in FIG. 2, pressurized fluid is admitted from conduit 84 to conduit 88 from which it enters chamber 90 between piston 62 and barrier member 56. The admission of pressurized fluid to chamber 90 forces piston 62 and piston rod 66 to the left relative to cylinder 52, however, the left or lower end of piston rod 66 is anchored at location 46 as shown in FIG. 1, therefore, the effect of such operation is to extend the cylinder 52 and the complete cylinder structure 50 along with piston 72 and rod 76 to the right, that is, upwardly in FIG. 1. Such extension continues if valve 36 remains open and the admission of pressurized fluid continues until piston 62 strikes closure member 53, and such operation partially raises bucket 24 relatively slowly but with a large ultimate force because of the large piston area on which the pressurized fluid acts.

A ball type relief valve indicated generally by the numeral 92 is located between chamber and another chamber 94 between barrier 56 and piston 72. The relief valve structure includes a larger bore 96 entering member 56 from the right, and a smaller bore 93 connecting chamber 90 with the larger bore 96 and forming a tapered seat 99 therebetween upon which a ball ltli) is seated. The ball 100 normally is held in place on the seat by means of a spring 102 which is secured in bore 96 in a suitable manner such as by snap ring 1%)4. The spring 102 is selected so that it holds the ball 100 in engagement with seat g9 and thus prevents the passage of fluid from chamber )6 to chamber 94 as long as piston 62 is moving. However, when piston 62 strikes closure member 58 and cannot move farther, the resulting rise in pressure in chamber 9% causes spring 102 to be compressed and fluid to be passed around ball 1% into chamber 94 where it causes piston 72 to move to the right and extend piston rod 76 out the right end of the actuator. As long as the pressurized fiuid is continued to be admitted from conduit 84 through valve 36, conduit 88 and chamber 90 and thence through the relief valve the piston 72 continues to move until it strikes closure member 60 which is the limit of operation of the actuator. At this time the boom arms 26 will have moved to the position indicated by the dot-dash lines in FIG. 1 and the bucket 24 will have been elevated to its maximum position. It will be appreciated that the latter increment of motion resulting from the action of piston 72 will be at a faster rate but at a lower force than the initial increment produced by the movement of piston 62 inasmuch as piston 72 is smaller in diameter and the same unit pressure of the pressurized hydraulic fluid thereby produces a smaller ultimate force. It will be appreciated too that the check valve prevents the entry of any hydraulic fluid directly from conduit 88 to chamber 94.

When it is desired to return boom arm 26 to its initial position the operator merely turns valve 86 clockwise 90 to interconnect conduit 88 with a conduit 106 which leads to the sump or reservoir for the hydraulic fluid. The hydraulic fluid then drains from chamber 94 through conduit 108 and check valve 110 to conduit 88, and at the same time drains from chamber 90 directly into conduit 88, and all the liquid drains from conduit 88 to drain conduit 106. Such draining of the chambers occurs by gravity and by the gravitational force exerted by the bucket and boom arms on the actuator. It will be recognized by those familiar with hydraulic devices that actuator 42a as illustrated in FIG. 2 is a single-acting device, that is, it is extended by force resulting from the pressurized hydraulic fluid, but it is retracted by gravity.

FIG. 3 shows an actuator which is indicated by the numeral 42b to distinguish it from the embodiment of FIG. 2. Many parts of actuator 42b are the same as actuator 42a, and such parts are indicated by the same numerals in FIG. 3 as the same parts in FIG. 2. Certain of the hydraulic circuit elements are different or function differently than the corresponding elements in FIG. 2 and these elements have been indicated either by the same number followed by a letter or by a different number. The embodiment of FIG. 3 is arranged so that the 'hydraulic actuator is double-acting. In addition, it is arranged so that the small piston 72 operates first followed sequentially by the large piston 62, and for this purpose the relief valve 92 is reversed.

A description of the operation of the embodiment of FIG. 3 should .suflice for an understanding of the manner in which this embodiment differs from that of FIG. 2. In FIG. 3 pressurized fluid is arranged to be admitted from conduit 84 by valve 86b to either a conduit 88b corresponding to line 88 of FIG. 2 or selectively to another inlet conduit 89, depending upon which way valve 8 6i) is turned from the position illustrated. If it is turned clockwise approximately 45 then passage 87 in the valve interconnects conduits 84 and 8&1), while if it is turned counterclockwise approximately 45 then pass-age 85 interconnects conduit 84 and conduit 89. Assume first that it is turned clockwise so that conduit 84 is interconnected with conduit 881). In this position pressurized fluid is admitted through conduit 88b to chamber 94 to extend the small piston 72 and its rod 76 until piston 72 abuts against closure member 60. Then the pressurized fluid goes through the relief valve 92 in the same manner described previously for the other embodiment into chamber 90 Where it is effective to extend the large piston 62. Check valve 11Gb in this embodiment prevents pressurized fluid from entering chamber 90 directly from the source. This arrangement produces a sequential operation in which the smaller force occurs first followed by the larger force as the boom arms approach the top position indicated by the dot-dash lines in FIG. 1. As the boom arms are approaching this position the moment arm through which the actuator is acting is getting smaller until when the upper position is reached the moment arm is indicated by the numeral 112 whereas the moment arm initially is indicated at 1-14, being approximately the distance between p-ivot points 30 and 48. It will be appreciated that the total load Which the machine can lift is determined by the product of the moment arm and the applied force, thus the machines lifting ability becomes less as the boom arm is raised sufiiciently to cause the moment arm to become less. However, by employing this invention in acoordance with the embodiment of FIG. 3 it is possible to increase the force near the end of the lifting operation to .counteract the reduction in the moment arm and thus increase the maximum lifting ability of the machine Without changing any of the other essential parts.

The embodiment of FIG. 3 as mentioned previously is double-acting. When it is desired to retract the actuator again the valve 86b is turned so that conduit 88b is connected by passage 87 in the valve to drain conduit 1% in order to drain the fluid from chamber 94 and also from chamber 90 through check valve 11Gb. At the same time passage 85 of the valve connects conduit 89 with the source of pressurized fluid, conduit 84. This admits.

pressurized fluid through opening 82 into the right end of the smaller cylinder, and at the same time admits fluid through an additional conduit 91 to the left end of the larger cylinder through opening 71. Thus the pressurized fluid is utilized to retract the pistons in the same manner as it was utilized to extend them originally.

With reference to the relief valve 92 in the actuator, it should be understood that the present invention is not limited to the ball type valve described and illustrated herein. Other valves which open only upon the occurrence of a predetermined pressure can be used in place of the relief valve disclosed if desired. Valve 92 as disclosed also acts as a check valve for the direction opposite to the direction of fluid flow through the valve, however, such check valve function is not essential to the present invention. If it is desired to utilize a valve which acts as a relief valve in one direction but does not act as a check valve in the other direction, such valve may be employed satisfactorily in this invention.

While two preferred embodiments of the invention have been described and illustrated herein, it will be appreciated that other modifications of the invention may be emplcyed. For example, some material handling machines have a single boom arm carrying the material engaging mean-s instead of a plurality of boom arms, and the pres- 6 ent invention is adaptable for such single boom arm inachines. It should be understood therefore that it is intended to cover by the appended claims all modifications falling within the true spirit and scope of the present invention.

I claim:

ii. A hydraulic actuator comprising a two part cylinder structure including a smaller cylinder portion and a larger cylinder portion interconnected by a combined support and barrier portion, the said support and barrier portion having an opening therethrough interconnecting the said two cylinder portions, a first piston reciprocabl-e in a first one of the said cylinder portions and forming with the said support and barrier portion a first chamber, a first piston rod connected to the said first piston and extending outwardly of the said first cylinder portion, a second piston .reciprocable in the said second cylinder portion and forming with the said support and barrier portion a second chamber, a second piston rod connected to the said second piston and extending outwardly of the said second cylinder portion, connections to a source of pressurized fluid including a valve for controlling fluid flow, a first conduit connecting the said valve with one of the said chambers to supply pressurized fluid selectively thereto, a relief valve in the said opening in the said support and barrier portion allowing the passage of fluid from the said one chamber to the other chamber only upon the occurrence of a predetermined fluid pressure in the said one chamber, a second conduit connecting the said other chamber with the said first conduit, and a check valve in the said second conduit permitting fluid flow thereth-rough only from the other chamber to the first conduit.

2. A hydraulic actuator comprising a twc-part cylinder structure including a smaller cylinder portion and a coaxially arranged larger cylinder portion interconnected by a combined support and barrier portion, the said support and barrier portion having an opening theret-hrough interconnecting the said two cylinder portions, a first piston reciprocable in a first one of the said cylinder portions and forming with the said support and barrier portion a first chamber, a first closure member closing the outer end of the said first cylinder portion and forming with the said first piston a second chamber, the said first closure portion having an opening therethrough, a first piston rod connected to the said first piston and extending outwardly of the said cylinder portion through the said opening in the first closure portion, a second piston reciprocable in the second said cylinder portion and formmg With the said support and barrier portion a third chamber, a second closure member closing the outer end of the said second cylinder portion and forming with the said second piston a fourth chamber, an opening through the said second closure member, a second piston rod connected to the said second piston and extending outwardly of the said second cylinder portion through the said opening in the second closure member, a control valve having a connection to a source of pressurized fluid, first conduit means connecting the said control valve with the said first and third chambers, a check valve in the said first conduit means permitting flow between the said third chamber and the said control valve only from the third chamber toward the control valve, second conduit means connecting the said central valve with the said second and fourth chambers, and a relief valve in the said opening in the said support and barrier portion allowing the passage of fluid from the said first chamber to the said third chamber only upon the occurrence of a predetermined fluid pressure in the said first chamber, whereby when the said control valve is turned to connect the source of pressurized fluid with the said first conduit means the said pistons move apart sequentially and When the control valve is turned to admit pressurized fluid to the said second conduit means the two pistons move to Ward their retracted positions simultaneously.

.3. An actuator for raising the boom arm of a material handling machine comprising, a two-part cylinder structure including a smaller cylinder portion and a larger cylinder portion interconnected by a barrier portion, the said barrier portion having an opening therethrough interconnecting the said two cylinder portions, a first piston operable in .a first one of the said cylinder portions and forming with the said barrier portion a first chamber, a first piston rod connected to the said first piston and extending outwardly of the said first cylinder portion, a second piston operable in the said second cylinder portion and forming a second chamber with the said barrier portion, a second piston rod connected to the said second piston and extending outwardly of the said second cylinder portion, a relief valve in the said opening in the barrier portion allowing the passage of fluid between the said two chambers in one direction only upon the occurrence of a predetermined pressure connection to a source of pressurized fluid including a valve for controlling fluid flow, a first conduit connecting the said valve with one of the said chambers to supply pressurized fluid selectively thereto, a second conduit connecting the said other chamher with the said first conduit, and a one-way check valve disposed in the said second conduit for permitting fiuid fiow only from the said other chamber to the said first conduit.

4. An actuator as specified in claim 3 in which the said relief valve is arranged in the said opening to admit fluid 8 from the said smaller cylinder portion to the said larger cylinder portion upon the occurrence of a predetermined pressure in the said smaller cylinder portion, and the said first conduit is connected to the said smaller cylinder portion.

5. An actuator as specified in claim 3 in which the said relief valve is arranged in the said opening to admit fluid from the said larger cylinder portion to the said smaller cylinder portion upon the occurrence of a predetermined pressure in the said larger cylinder portion, and the said first conduit is connected to the said larger cylinder portion.

, References Cited by the Examiner UNITED STATES PATENTS 851,277 4/07 Clark 303-6 1,677,860 7/28 Ferris -97 2,282,556 5/42 Bowen "91-167 2,449,212 9/48 Fraga 214-14O 2,684,162 7/54 Hendrickson et al. 214-131 2,808,017 10/57 Killebrew.

2,843,213 7/58 Schwartz 214-131 X 2,865,175 12/58 Gondek 60-97 3,061,117 10/62 Kruse 214- X JULIUS E. WEST, Primary Examiner.

HUGO SCHULZ, Examiner. 

1. A HYDRAULIC ACTUATOR COMPRISING A TWO-PART CYLINDER STRUCTURE INCLUDING A SMALLER CYLINDER PORTION AND A LARGER CYLINDER PORTION INTERCONNECTED BY A COMBINED SUPPORT AND BARRIER PORTION, THE SAID SUPPORT AND BARRIED PORTION HAVING AN OPENING THERETHROUGH INTERCONNECTING THE SAID TWO CYLINDER PORTIONS, A FIRST PISTON RECIPROCABLE IN A FIRST ONE OF THE SAID CYLINDER PORTIONS AND FORMING WITH THE SAID SUPPORT AND BARRIER PORTION AND FORMING WITH FIRST PISTON ROD CONNECTED TO THE SAID FIRST PISTON AND EXTENDING OUTWARDLY OF THE SAID FIRST CYLINDER PORTION, A SECOND PISTON RECIPROCABLE IN THE SAID SECOND CYLINDER PORTION AND FORMING WITH THE SAID SUPPORT AND BARRIER PORTION A SECOND CHAMBER, A SECOND PISTON ROD CONNECTED TO THE SAID SECOND PISTON AND EXTENDING OUTWARDLY OF THE SAID SECOND CYLINDER PORTION, CONNECTIONS TO A SOURCE OF PRESSURIZED FLUID INCLUDING A VALVE FOR CONTROLLING FLUID FLOW, A FIRST CONDUIT CONNECTING THE SAID VALVE WITH ONE OF THE SAID CHAMBERS TO SUPPLY PRESSURIZED FLUID SELECTIVELY THERETO, A RELIEF VALVE IN THE SAID OPENING IN THE SAID SUPPORT AND BARRIES PORTION ALLOWING THE PASSAGE OF FLUID FROM THE SAID ONE CHAMBER TO THE OTHER CHAMBER ONLY UPON THE OCCURRENCE OF A PREDETERMINED FLUID PRESSURE IN THE SAID ONE CHAHAMBER, A SECOND CONDUIT CONNECTING THE SAID OTHER CHAMBER WITH THE SAID FIRST CONDUIT, AND A CHECK VALVE IN THE SAID SECOND CONDUIT PERMITTING FLUID FLOW THERETHROUGH ONLY FROM THE OTHER CHAMBER TO THE FIRST CONDUIT. 